iphone - 向 iPhone 中的 UIImage 添加类别

Question

我想向 UIImage 添加一个类别并将其链接到我的 iPhone 应用程序，但出现此错误:

(unrecognized selector)

我的代码:DoingStuff.h

#import <UIKit/UIKit.h>

@interface UIImage (DoingStuff)

- (UIImage *)performStuff;

@end

DoingStuff.m

#import "DoingStuff.h"

@implementation UIImage (DoingStuff)

- (UIImage *)performStuff 
{
    // My code here
}

@end

但是当我运行我的程序时，我得到了这个:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIImageView performStuff:]: unrecognized selector sent to instance 0x4b415d0'

Answer 1

[UIImage performStuff]; // Correct call

不是

[UIImageView performStuff]; // It is a UIImage category not UIImageView

对于初学者来说。

所以你会做这样的事情......

UIImage* image = [UIImage imageNamed:@"test"];
[image performStuff];